The present invention relates to heater systems. More particularly, the present invention relates to in-line fluid heater systems used to heat ultra pure fluids, such as water and aggressive process chemistries.
The art of heating ultra pure water and other aggressive process chemistries for use in the semiconductor, solid state, disk drive, and other process sensitive industries is well known. The performance of such process fluids improves when they are used at higher temperatures. The target temperature for heating systems in this area has been 200xc2x0 C.
There are already many conventional designs for process fluid heating systems utilizing heat sources such as resistive metal elements, halogen infrared light, or process heat exchangers. Such systems have several drawbacks. Many of these systems are limited in the proximity to which they can place the element in relation to the medium being heated.
One prior art heating system uses a type of resistive ceramic material that radiates heat when electricity is applied. This type of system requires specialized controls to operate the heater. The heating element itself is also thermally sensitive in that rapid heating or cooling of the element can damage it. This type of system will then experience poor performance with a system that has slow response to heating requirements. In practice, this leads to high failure rates for this type of heating system and expensive repair costs.
Another example of a heating system that is intended to meet the needs of the above-mentioned processes utilizes halogen lamps that emit short to medium wave infrared radiation which is exposed to the fluid. By nature, it is difficult to utilize all of the infrared energy emitted by this type of system. FIG. 1 illustrates such a heating system 10. Fluid 12 to be heated passes through a tube 14. A halogen lamp 16, or the like, is placed adjacent to the tube 14 for emitting short to medium wave infrared radiation into the fluid 12. As an improvement, a reflector 18 is disposed around the halogen lamp 16 such that the radiation emitted away form the tube 14 is reflected back into the system 10.
Such a heating system is described in U.S. Pat. No. 5,790,752 to Anglin et al. In the Anglin et al. heating system, lamps are placed around the outside of a fluid vessel, or tube, through which the fluid flows. The fluid tube is preferably transparent to infrared radiation. Due to the fact that the majority of the infrared radiation originating from the lamps are not directed at the fluid to be heated, the design relies upon reflectors to capture and redirect a portion of this lost energy. While this provides some improvement and increases sufficiency somewhat, not all of the energy is captured and some is lost in the reflector itself as heat. The reflectors are typically gold-plated reflectors, increasing the expense of the system. Also, due to the fact that the radiant energy is reflected onto the halogen lamps, the lamps must continually be replaced. In many systems, lamp replacement is not an easy task and requires considerable labor, increasing the operational costs of the system.
Accordingly, there is a need for a heating system with rapid response, lower operational costs, and greater reliability, while also maintaining the ultra-purity required by the above-mentioned processes. The present invention fulfills these needs and provides other related advantages.
The present invention resides in a heating system comprising a heater assembly having a lamp module and a fluid vessel whereby the lamp module heats a fluid within the fluid vessel. The lamp module produces heat by dissipating electrical energy via a plurality of lamps, such as infrared emitting lamps. The lamps are integrated as part of a lamp module which simplifies the replacement procedure for the lamps.
The in-line fluid heating system of the present invention generally comprises a lamp module including a plurality of heating lamps spaced from one another. A fluid vessel has a fluid inlet and outlet so as to pass fluid therethrough. The fluid vessel is configured to slidably accept the lamp module therein. In a particularly preferred embodiment, the fluid vessel comprises a central tube defining the inlet in fluid communication with an outer envelope coaxial to the central tube and defining the outlet. The lamp module is generally cylindrical and removably disposed between the central tube and the outer envelope. Thus, the fluid is heated as it passes through the central tube and the outer envelope.
The fluid vessel is preferably comprised of a durable and transparent material, such as quartz. In a particularly preferred embodiment, a reflector substantially surrounds the fluid vessel for reflecting energy back into the fluid vessel. Insulation may surround the reflector and fluid vessel to further retain heat within the fluid vessel.
A corrosion resistant housing, such as one comprised of a fluorocarbon plastic, sealingly surrounds the insulation, reflector, fluid vessel and lamp module. Preferably, sensors are associated with the fluid vessel and lamp module for detecting temperature and any fluid leaks of the pressurized fluid in the fluid vessel.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate by way of example, the principles of the invention.